text: The first C–H activation reaction is often attributed to Otto Dimroth, who in 1902, reported that benzene reacted with mercury(II) acetate (See: organomercury).  Many electrophilic metal centers undergo this Friedel-Crafts-like reaction. Joseph Chatt observed the addition of C-H bonds of naphthalene by Ru(0) complexes.
  Chelation-assisted C-H activations are prevalent. Shunsuke Murahashi reported a cobalt-catalyzed chelation-assisted C-H functionalization of 2-phenylisoindolin-1-one from (E)-N,1-diphenylmethanimine.
  In 1969, A.E. Shilov reported that potassium tetrachloroplatinate induced isotope scrambling between methane and heavy water. The pathway was proposed to involve binding of methane to Pt(II). In 1972, the Shilov group was able to produce methanol and methyl chloride in a similar reaction involving a stoichiometric amount of potassium tetrachloroplatinate, catalytic potassium hexachloroplatinate, methane and water. Due to the fact that Shilov worked and published in the Soviet Union during the Cold War era, his work was largely ignored by Western scientists. This so-called Shilov system is today one of the few true catalytic systems for alkane functionalizations.
  In some cases, discoveries in C-H activation were being made in conjunction with those of cross coupling. In 1969, Yuzo Fujiwara reported the synthesis of (E)-1,2-diphenylethene from benzene and styrene with Pd(OAc) and Cu(OAc), a procedure very similar to that of cross coupling. On the category of oxidative addition, M. L. H. Green in 1970 reported on the photochemical insertion of tungsten (as a CpWH complex) in a benzene C–H bond and George M. Whitesides in 1979 was the first to carry out an intramolecular aliphatic C–H activation
  The next breakthrough was reported independently by two research groups in 1982. R. G. Bergman reported the first transition metal-mediated intermolecular C–H activation of unactivated and completely saturated hydrocarbons by oxidative addition. Using a photochemical approach, photolysis of Cp*Ir(PMe)H, where Cp* is a pentamethylcyclopentadienyl ligand, led to the coordinatively unsaturated species Cp*Ir(PMe) which reacted via oxidative addition with cyclohexane and neopentane to form the corresponding  complexes, Cp*Ir(PMe)HR,  where R = cyclohexyl and neopentyl, respectively. W.A.G. Graham found that the same hydrocarbons react with Cp*Ir(CO) upon irradiation to afford the related  complexes Cp*Ir(CO)HR, where R = cyclohexyl and neopentyl, respectively. In the latter example, the reaction is presumed to proceed via the oxidative addition of alkane to a 16-electron iridium(I) intermediate, Cp*Ir(CO), formed by irradiation of Cp*Ir(CO).
  The selective activation and functionalization of alkane C–H bonds was reported using a tungsten complex outfitted with pentamethylcyclopentadienyl, nitrosyl, allyl and neopentyl ligands, Cp*W(NO)(η-allyl)(CHCMe).
  In one example involving this system, the alkane pentane is selectively converted to the halocarbon 1-iodopentane. This transformation was achieved via the thermolysis of Cp*W(NO)(η-allyl)(CHCMe) in pentane at room temperature, resulting in elimination of neopentane by a pseudo-first-order process, generating an undetectable electronically and sterically unsaturated 16-electron intermediate that is coordinated by an η-butadiene ligand. Subsequent intermolecular activation of a pentane solvent molecule then yields an 18-electron complex possessing an n-pentyl ligand. In a separate step, reaction with iodine at −60 °C liberates 1-iodopentane from the complex.